The British Columbian (BC) coast spans a 1000 km range of complex coastal geographic and oceanographic conditions that include thousands of islands, glacial carved fjords, exposed rocky coastline, and warm inlands seas. Very little is known about invertebrate fouling communities along the BC coast as studies are usually localised, focused in ports, or are conducted in the intertidal environment. This study provides the first high resolution study of invertebrate fouling communities of the BC coast by describing the identity, richness, diversity, and community composition of invertebrate fouling communities. Studying fouling communities on artificial surfaces was useful because the limiting resource (space) was defined, the researcher could control the timeframe, the samples were easily transported long distances, and the system can be easily replicated. Settlement structures were deployed in the spring of 2007 from the floating structures of marinas, docks, and aquaculture facilities. The deployment sites spanned a range of coastal environments from the Alaskan border to the southern tip of Vancouver Island, and included the Queen Charlotte Islands and Vancouver Island. The settlement arrays were collected roughly five months following deployment. Samples were transported back to the laboratory where all organisms present on the settlement arrays were identified to the lowest taxonomic level possible and their relative abundance recorded. The invertebrate fouling community was very species rich with 171 species identified and an additional 34 categories of unresolved taxa. This high richness may be attributed to the fact that the settlement arrays sampled the community as a whole, including motile and rare species. The richness per sample ranged from 1 to 29 species with the average being 12 species, of which more than one (1.25) was introduced to the BC coast. This invertebrate fouling community was dominated by relatively few species. Only 20% of the sessile species had an average cover over 1% and only 13% of the motile species had an average count over 0.5 individuals per sample. Of the sessile species, the Mytilus sp. complex was the most common with an average coverage of 35%. The Mytilus sp. complex was also found in 78% (126/162) of all samples. There were eleven introduced and twelve cryptogenic species identified in this study. Introduced species represented 30% of the dominant (=most abundant) sessile species and 20% of the dominant motile species study. The introduced and cryptogenic species were more abundant than native species when comparing abundance based on their distributions in the samples. The prominence and abundance of the introduced species in these communities may be an artefact of studying anthropogenic sites. However, it underscores the fact that the establishment and spread of non-native species are continuing along our coast, and that the strong competitive ability of a number of these species may have negative ecological and economic impacts. There were strong similarities in community composition across all geographic areas of the BC (Strait of Georgia-SOG, Juan de Fuca Strait- JFS, west coast of Vancouver Island-WCVI, Johnstone Strait-JS, and the north coast of the mainland-NC). The most common species assemblage was the Mytilus sp. complex and its associated species. The species assemblages observed across numerous geographic areas included species that were strong space competitors, had ranges that included the length of our study area, had key reproductive periods during the sampling period, and were able to recruit to artificial substrates. Anthropogenic structures may also be partially responsible for the strong similarities in community composition along the coast as we may be sampling species that are best adapted to these environments. Additionally, anthropogenic structures and activities may serve as vectors of species dispersal. Pairwise comparisons showed that the WCVI differed from the JFS and QCI in community composition in that the WCVI was strongly influenced by the Mytilus sp. community but the JFS and QCI were influenced by introduced and cryptogenic species. This study is the first to examine fouling communities that span the length of the BC coast. The data collected can be used as a baseline of comparison for future studies on subjects such as climate change, human mediated species introductions, and anthropogenic disasters. / Graduate

Some aspects of the biology of Pacifastacus leniusculus and Astacus leptodactylus have been compared. The literature survey shows that considerably more studies have been carried out on P. leniusculus than A. leptodactylus. Although no major differences have been found in the morphology of appendages and mouthparts of the species, structural differences have been found in the abundance of setae on the second maxilliped, in the number of teeth on the mandibles and the crista dentata, and form of the chelipeds. Studies on the environmental tolerance of the species show that both species are able to survive in saline water for long periods of time but they can only increase in number in low salinities. Both species can survive over a wide range of temperatures, but they cannot tolerate temperatures of 34 °C after stepwise acclimation. Although the results do not show a clear difference in the tolerance of P. leniusculus and A. leptodactylus to low oxygen, there are some indications that A. leptodactylus is more tolerant of decreased oxygen tensions than P. leniusculus. By using a non-invasive heart beat monitor on crayfish it has been observed that the frequency of heart beats is extremely variable and can be affected by many factors, such as temperature and salinity. Juveniles of the two species can have a significant impact on plant and macroinvertebrate communities. The results also show that both species can have a negative effect on the recruitment of fish populations in freshwaters by eating fish eggs. Competition experiments show that both juveniles and adults of P. leniusculus are significantly more aggressive than those of A. leptodactylus. The results also show that A. leptodactylus would be eliminated by P. leniusculus if they met in a wild. Adults of the species prey on their juveniles, except the brooding females with stage 2s. This predation occurs in the presence of adequate nutrition. Non-predatory behaviour of the brooding females may indicate the presence of pheromones in the species. Reproductive efficiency of the populations of the species in Britain is as good as any studied elsewhere. In comparison to A. leptodactylus, P. leniusculus has more eggs, but smaller in size. Pleopodal egg development of the species can be reduced from seven months to three months with temperature acclimation, but photoperiod is not a factor in reducing pleopodal egg development. In both species sexual dimorphism was observed between males and females. Males of both species and females of P. leniusculus exhibit allometric or isometric growth during their lives but female A. leptodactylus exhibits isometric growth throughout. Comparison of body parameters shows that P. leniusculus can be considered as a morphologically better species to adapt to environmental conditions than A. leptodactylus because it has large and heavy chelae, and heavy body weight. Both species grow fast, but because P. leniusculus hatches earlier it has an advantage over A. leptodactylus and has bigger juveniles by the end of the first summer. In both species males produce significantly more claw meat than females. Although A. leptodactylus produces significantly more tail meat, males of P. leniusculus produce significantly more claw and total meat. Significant differences occur in the tail meat yield of female A. leptodactylus and in the claw meat yield of female P. leniusculus, but males produce similar amount of meat in winter and summer. The Swedish trappy is very effective method of catching both species over a certain size. Day and night catches show that both species are very active during the day and night.

The only species of crayfish native to the British Isles, i.e. Austropotamobius pallipes, is presently widely distributed throughout much of England, Wales and Ireland. The main controlling factor behind this distribution is the predominantly "bicarbonate" freshwater system of the British Isles. In geological terms, native crayfish are generally found in areas of chalk, carboniferous or magnesium limestone, or drift deposits of boulder clay. More recently, native crayfish have been affected by a general decline in the quality of Britain's freshwater system largely due to sewage effluent and agricultural. By far the majority of native crayfish records are associated with water bodies of very good or good quality, with the result that many populations of A. pallipes are isolated in small, good quality headwaters, due to the degree of pollution in the main rivers acting as "chemical barriers". The last two decades have seen a number of alien species of crayfish imported into England and Wales for aquaculture and culinary purposes. Deliberate and accidental introductions have resulted in the establishment of populations of these species in the wild, the most widespread being the North American signal crayfish Pacifastacus leniusculus and the European slender-clawed crayfish Astacus leptodactylus. An important and devastating consequence of the introduction of alien species of crayfish has been the spread of the crayfish plague fungus Aphanomyces astaci, possibly initiated by infected P. leniusculus. Both A. pallipes and A. leptodactylus are susceptible to the disease, with the result that populations of A. pallipes have been eliminated from, whole lengths of river, such as the River Kennet and the Hampshire River Avon. The nature of the disease and the ease with which it is spread means that crayfish is an ongoing problem in England and Wales, with new populations of A. pallipes regularly becoming affected. The distribution of alien species in the British Isles is an artificial one, initially determined by man, although consideration of water quality may have determined the choice of aquaculture sites. However, established populations of alien species in the wild will be subject to the same constraints as A. pallipes, which will affect their subsequent spread and distribution in the freshwater system of England and Wales. A greater tolerance of environmental factors may allow alien species to inhabit waters not currently occupied by the native species, such as polluted or estuarial waters, and possibly threaten populations of A. pallipes protected by "chemical barriers". This study investigated and compared some of the environmental tolerances of A. pallipes, A. leptodactylus and P. leniusculus and consisted of two parts: 1.) Comparison of the tolerance of A. pallipes, A. leptodactylus and P. leniusculus to four common pollutants; chloride, copper, ammonia and lindane, using lethal and sublethal toxicity tests. No species was found to have a greater overall pollution tolerance on the basis of the toxicants used in this study. Median lethal concentrations (LC50) obtained from lethal studies with stage II juveniles indicated that A. leptodactylus juveniles were most tolerant of chloride, but were very sensitive to lindane. P. leniusculus stage II juveniles were least tolerant of chloride, but of equal or greater tolerance when tested in larger juvenile stages, and were most tolerant of copper. A. pallipes juveniles were very sensitive to copper, and all three species showed a similar sensitivity to ammonia. However, episodic experiments with ammonia and copper indicated that differential short-term tolerance to toxicants, i.e. less than 24 hours, may be important in determining the outcome of episodic pollution events on crayfish populations. Salinity studies indicated high resistance to chloride, with all three species able to tolerate salinities up to 50% seawater, implying freshwater crayfish may be able to tolerate estuarine conditions. Accumulation studies with P. leniusculus inferred resistance to high levels of copper in the environment, with a substantial storage capacity for the metal and a regulatory mechanism for excretion of excess amounts. However, establishment of populations under high saline or high copper conditions would be limited by the lower tolerance of early life stages. Similarly, sublethal studies implied that sublethal toxicant effects on early life stages may be important in determining presence or absence of crayfish from a waterbody, through effects on recruitment. 2.) Comparison of the thermal relations of A. pallipes, A. leptodactylus and P. leniusculus, using tolerance, growth and respiration experiments. Results from tolerance experiments showed that P. leniusculus had a greater overall thermal tolerance, so is more resistant to changes in environmental temperature, such as in waters affected by thermal discharges or in waters affected by drought and reduced flow. In growth experiments P. leniusculus grew faster at all temperatures tested and was predicted to grow at temperatures unsuitable for the other species. Therefore, P. leniusculus would not only be able to survive and grow in conditions unsuitable for A. pallipes and A. leptodactylus, but will also grow faster where favourable conditions exist for all three species. Field experiments showed that, although P. leniusculus juveniles were smaller on release from the female, they were released earlier and their faster growth rate allowed them to maintain a distinct size advantage over A. pallipes juveniles, which was very marked by the end of the growing season. Large size is a key element in the attributes leading to competitive success in other crayfish species. Field observations on mixed populations of plague-free P. leniusculus and A. pallipes indeed show that signal crayfish are superior competitors, eventually eliminating A. pallipes. Therefore temperature effects may be important in determining the outcome of competition in mixed crayfish populations.

The behavioural responses of aphid parasitoids (Hymenoptera: Braconidae: Aphidiinae) to aphid sex pheromones were investigated in the laboratory and field. In a wind tunnel bioassay, Aphidius eadyi, Aphidius rhopalosiphi, Diaeretiella rapae, Ephedrus plagiator, Praon myzophagum and Praon volucre responded to the aphid sex pheromone components nepetalactone and nepetalactol. P. myzophagum reared on two different host aphid species showed different responses to combinations of nepetalactone and nepetalactol in the wind tunnel, indicating that long term laboratory rearing may influence parasitoid responses to aphid sex pheromones. The ability of two aphid parasitoids to learn aphid sex pheromones through prior exposure in the presence of host aphids was investigated. The generalist E. plagiator showed evidence of associative learning, whereas the specialist Aphidius ervi did not. When A. ervi was exposed to the pheromone without contact with host aphids, the parasitoid response was reduced by habituation. Exposure to aphid sex pheromone during laboratory host attack trials had no effect on the host attack behaviour of A. ervi. In laboratory cage experiments, aphid sex pheromone lures increased the retention of A. rhopalosiphi, but not by Praon volucre, on aphid-infested plants. In a wind tunnel bioassay, aphid sex pheromone enhanced the attraction of A. ervi to a plant-host complex. In the field, aphid sex pheromone lures increased parasitisation rates by A. rhopalosiphi and P. volucre on aphid-infested potted plants. A series of potted plant experiments indicated that the pheromone may increase parasitisation of aphids by A. rhopalosiphi, but not P. volucre, at a distance of 1m away from the lure. The effect of baiting plots of winter wheat with aphid sex pheromone was investigated in two field experiments. In 1996, the number of parasitoid mummies was higher in baited plots than in unbaited plots, and the synchrony between aphid and parasitoid populations was closer in baited plots. In 1997, aphid sex pheromone had no effect on parasitisation levels. The results are discussed in the context of developing a novel aphid control strategy based on the use of aphid sex pheromones to manipulate parasitoid populations.

The ecology of Austropotamobius pallipes (Lereboullet) from Markfield Quarry and the River Leen was described. Studies included: 1. Biology. (i) Timing of life cycle events. They related to ambient conditions, especially temperature. (ii) Fecundity. Individual fecundity increased with female size. Population fecundity related to population density. (iii) Local distribution. This related to hide availability. Gross water quality affected the distribution of the river crayfish. 2. Population dynamics. (i) Population size/density. That of the Quarry was greater, and related to hide availability. Seasonal variations in population size were temperature dependent. (ii) Population structure. - size structure varied between populations due to collection techniques. It varied seasonally due to recruitment and differential catchability of certain sub-populations. - sex ratios varied seasonally due to reduced foraging by ovigerous females. - disease and damage occurred for all sizes/sexes. Thelohania contejeanii was absent from Markfield Quarry but increased in the Leen during the study period. 3. Growth. (i) At moulting. Sexual differences were absent for the absolute increment, but males grew quicker due to greater moult frequencies. Growth rates of river animals were greatest due to a longer growing season and smaller population density. (ii) Relative growth of body parts. No consistent population differences occurred, but of significance were chelae and rostrum sizes. Sexual dimorphism occurred for certain variables, notably the chelae and abdomen width. The effects of cadmium and Lindane upon A. pallipes were examined. Studies included: 1. Survival. Juveniles were 10 times more sensitive than adults. Lindane was the most toxic. 2. Uptake and depuration. Cadmium accumulated chiefly in the gills. Some evidence for its translocation to other tissues was found. No sexual differences occurred. Lindane accumulated chiefly in the hepatopancreas. Evidence for its translocation and depuration was shown. No sexual differences occurred. 3. Tissue oxygen consumption. Both toxicants caused a depression. Recovery occurred with time. The results were related to the levels of toxicant in Midlands waters.

This study investigated how the predicted increase in global temperature would affect the interaction between the cereal aphid, Sitobion avenae F. (Hemiptera: Aphididae), and its coccinellid predator, Coccinella septempunctata L. (Coleoptera: CoccinelIidae). A model describing the summer population dynamics of S. avenae (Carter et al., 1982) was modified and updated. New equations describing the dependence of aphid development and reproduction on temperature were formulated. A new submodel, describing the population dynamics of C. septempunctata, was incorporated into the model. The predatory interaction between C. septempunctata and S. aveizae was described using a modified form of the temperature-mediated functional response equation proposed by Mack et al. (1981). A sensitivity analysis showed that the output of the model, which compared well with field observations, was not greatly affected by small changes to the parameters of the equations used in the submodel. Stochastic elements were incorporated into the model; aphid and coccinellid immigration were simulated by sampling randomly from distributions fitted to observed patterns of immigration. Three temperature regimes: hot, moderate and cold, were defined by ranking and splitting the years from 1965 to 1992 according to the mean temperature between April and August. The temperature data from the years assigned to each regime were then used to formulate an equation to describe the daily temperatures within the five months. The model was run for each regime, and the output showed that both coccinellid predation and increased temperatures caused a decrease in aphid abundance. The model also highlighted several more subtle effects of increased temperature on the interaction between S. avenae and C. septempunctata. The importance of the model predictions for future control of aphid populations in cereal crops is discussed.

No description available.

In certain species of cricket and bushcricket (Orthoptera; Ensifera), the male transfers an elaborate spermatophore to the female at mating. This consists of a sperm-containing ampulla and an often substantial, sperm-free, gelatinous mass known as the spermatophylax. After mating, the female eats the spermatophylax before consuming the ampulla. The spermatophylax is particularly well developed in the bushcrickets (Tettigoniidae) and can contribute to a loss of as much as 40% of male body weigh at mating in some species. Recently, there has been considerable debate over the selective pressures responsible for the evolution and maintenance of the spermatophylax and other forms of nuptial feeding in insects. Two different, though not mutually exclusive, functions have been suggested for the spermatophylax: 1) nutrients from the spermatophylax may function to increase the weight and\or number of eggs laid by the female, i.e. may function as paternal investment; 2) the spermatophylax may function to prevent the female from eating the ampulla before complete ejaculate transfer, i.e. may be regarded as a form of mating effort. In this study, a comparative approach combined with laboratory manipulations were used in an attempt to elucidate the selective pressures responsible for the origin, evolutionary enlargement and maintenance (= function) of the spermatophylax in bushcrickets. The results suggest that the spermatophylax originated as an adaptation to maximise ejaculate transfer by countering the tendency of females to eat the ampulla prematurely. The spermatophylax appears to be analogous to a range of adaptations found in males of the sub-order Ensifera, which may be interpreted as functioning to maximise ejaculate transfer. These adaptations include prolonged copulation following spermatophore transfer, feeding the female with glandular secretions following spermatophore transfer, post-copulatory mate guarding and multiple copulations with the same female. The occurrence of prolonged copulation following spermatophore transfer appears to be associated with the total loss of the spermatophylax in the meconematine bushcricket Meconema and with the considerable reduction in spermatophylax size in the ephippigerine bushcricket Uromenus rugiscollis. This supports the hypothesis that prolonged copulation and the spermatophylax are analogous in function. The subsequent evolutionary enlargement of the spermatophylax appears to have accompanied the evolutionary enlargement of ejaculate volume and sperm number, i.e. appears to have proceeded to facilitate the transfer of larger ejaculates. A comparative study of 43 species of bushcricket revealed a positive relationship, across taxa, between evolutionary changes in spermatophylax size and changes in ampulla size (i.e. ejaculate volume) and sperm number, with male body weight controlled for. The current function of the large spermatophylax appears to be the same as that of the small spermatophylax, i.e. to ensure complete sperm \ ejaculate transfer. No significant difference in the shape of the sperm transfer curve relative to the mean duration of spermatophylax consumption was found between Leptophyes punctatissima (small spermatophylax) and L.laticauda (large spermatophylax). Furthermore, in L.laticauda, males appear to adjust the size of the spermatophylax in relation to the amount of sperm or volume of ejaculate they are able to produce: a positive relationship was found between spermatophylax mass and sperm number and between spermatophylax mass and ampulla mass (i.e. ejaculate volume). The possibility that the spermatophylax additionally functions as paternal investment cannot, however, be ruled out on this basis. In order for male-donated nutrients to function as paternal investment they must 1) have a positive effect on offspring fitness and\or number and 2) the nutrient donating male must stand to fertilise most or all of the offspring which benefit from his nutrients. A positive effect of spermatophylax consumption on egg weight and\or number has previously been documented in some species of bushcricket, though has not been found in others. In this study, no effect of spermatophylax consumption on female reproductive output was found in L.punctatissima, L.laticauda, or Steropleurus, even when, in the latter two cases, females were maintained on a restricted diet. Furthermore, in L.punctatissima and Steropleurus stali (though not in L.laticauda) it appears that the spermatophylax-donating male is unlikely to fertilise eggs in which his nutrients might be incorporated, in light of the short female re-mating interval, the pattern of last-male sperm precedence and the pattern of oviposition. The enormous spermatophylax of S.stali is unlikely, therefore, to function as paternal investment. Recent studies suggest that in a number of other bushcricket species, including some with very large spermatophylaxes, the spermatophylax is also unlikely to function as paternal investment for the above reasons. In conclusion, while the paternal investment hypothesis lacks generality, the ejaculate-protection hypothesis seems to be more widely applicable and appears to successfully account for the origin, evolutionary enlargement and current function of the spermatophylax in bushcrickets.

The host-parasite relationship of the hookworm Ancylostoma ceylanicum was explored in a hamster model system, focusing on intestinal mucosal responses to infection. Primary infection induced a rapid reduction in villous height culminating in excess of 75% reduction by day 35. Crypts of Lieberkuhn increased in depth achieving maximum depth by day 35. Mitotic figures in crypts and mast cells increased until day 28. Goblet cells increased continuously from background levels of 50 cell/mm² to exceed 300 cells/mm² by day 42. Paneth cell numbers declined in infected animals. Termination of infection by anthelmintic restored background values of intestinal architecture and goblet cell numbers within 7 days, but mast cells took longer and Paneth cell numbers increased beyond values in naïve controls. Mucosal changes are therefore dependent on the presence of worms, intensity of infection and change dramatically with time. Mucosal changes were studied in hamsters experiencing secondary infections following anthelmintic abbreviation of the immunizing infection, superimposed challenge infection and trickle infections. The kinetics of the responses were compared to animals experiencing primary infections and naive controls. Among the findings were: 1) continuous reduction in villous height and a marked increase in crypt depth from day 10 after challenge in abbreviated primary-challenged hamsters compared to little change in hamsters given superimposed challenge. 2) marked mast, goblet, and Paneth cell and eosinophil responses. 3) less intense mast cell responses in abbreviated primary-challenged compared to superimposed challenge animals 4) after a superimposed challenge poor goblet cell responses because levels were already high at the time of challenge, little change in Paneth cells but intense eosinophil responses 5) slower changes in mucosal architecture and mast cell responses in trickle-infected animals eventually exceeding those in primary infected animals. 6) less marked goblet and Paneth cell responses in trickle-infected groups but more intense, persistent increases in eosinophils Cyclosporin A's (CsA) usefulness as an immunosuppressive therapy for blocking T cell control of immunity was explored. However, CsA turned out to have marked anthelmintic properties and reductions in worm burden confounded the interpretation of mucosal changes.

Multitrophic and intraguild interactions influence the success of biological control. The interactions between Acyrthosiphon pisum, three natural enemies (Pandora neoaphidis, Coccinella septempunctata and Aphidius ervi) and the host plant, Vicia faba, were assessed. Volatiles released from aphid-damaged plants had a direct effect on P. neoaphidis indicating they may act as synomones. However, volatiles did not increase efficacy of the fungus suggesting it is not a bodyguard species. Transmission was greatest during plant colonisation by aphids and was not affected by plant condition. Infection by P. neoaphidis had a direct negative effect on the fitness of the aphid through reduced reproduction and early host death. Avoidance of infected colonies by predators and parasitoids could reduce the effectiveness of guilds of natural enemies for biological control. However, at the laboratory scale A. ervi and C. septempunctata did not detect infection and entered and foraged in infected aphid colonies. Aphidius ervi spent longer searching for hosts on plants that had been damaged by aphid feeding (and were emitting aphid-induced species-specific volatiles) and this may increase fungal transmission. Coccinella septempunctata and A. ervi significantly reduced populations of A. pisum when introduced as individual species whereas P. neoaphidis had no effect on aphid population size. Foraging by both C. septempunctata and A. ervi increased the abundance and distribution of P. neoaphidis which may be sufficient to initiate an epizootic. The benefits of increased transmission by C. septempunctata outweighed the fitness costs to the fungus of intraguild predation. Pandora neoaphidis was associated with a decrease in the reproductive success of A. ervi, which was further reduced as the competitive advantage of the fungus increased. This could result in competitive exclusion of the parasitoid. Poly tunnel experiments confirmed that A. ervi did not discriminate between infected and uninfected aphid colonies at this spatial scale. However, A. ervi did not incur a fitness cost from foraging in patches containing the fungus. These results indicate that C. septempunctata and P. neoaphidis may be effective as multi-species biocontrol agents. In contrast, competition between P. neoaphidis and A. ervi may reduce their overall effectiveness as control agents. Further work is required at larger spatial scales and over several generations of both the pest and natural enemy species to confirm these interactions. The implications of these results for the use of P. neoaphidis as part of a multi-species biological control program are discussed.